Rheologists are encouraged to join in the development of a proposed new practice that will help standardize calibration of rotational rheometers to obtain accurate normal force measurements.
ASTM WK33687, Practice for Normal Force Calibration for Rotational Rheometers, is being developed by Subcommittee E37.08 on Rheology, part of ASTM International Committee E37 on Thermal Measurements. The standard will be used by both producers and end users of rotational rheometers.
Kenneth Aniunoh, E37.08 chairman and senior product specialist, Shimadzu Scientific Instruments, explains there is a current trend in industry toward the use of normal force measurements for characterizing the viscoelastic properties of materials. Normal force measurements, in rotational rheometers, provide an indication of the normal stresses generated in a material undergoing deformation.
“Normal force measurements can be used to characterize material viscoelasticity and also for quality control,” says Aniunoh. “A layman example of normal force/normal stress effects is the rod climbing phenomena or Weissenberg effect in which, for instance, we notice that bread dough climbs a stirring rod whereas water and glycerol flows outward from a stirrer. The behavior of the bread dough is due to normal stresses generated in the dough.”
All interested parties are invited to join in the activities of E37.08, which has also developed ASTM E2510, Test Method for Torque Calibration or Conformance of Rheometers.
ASTM International welcomes and encourages participation in the development of its standards. For more information on becoming an ASTM member, visit www.astm.org/JOIN.
ASTM Committee E37 Next Meeting: Aug. 10-11, in conjunction with the North American Thermal Analysis Society Annual Conference, Des Moines, Iowa
Technical Contact: Kenneth Aniunioh, Shimadzu Scientific Instruments, Laurel, Md., Phone: 864-633-7690; kenebaano@yahoo.com
ASTM Staff Contact: Thomas O’Toole, Phone: 610-832-9739; totoole@astm.org
ASTM PR Contact: Barbara Schindler, Phone: 610-832-9603; bschindl@astm.org
Release #8923